Most of the cutaneous diseases are generally accompanied by itching. Suppression and relief of such itching are one of the most important tasks in the clinical practice of today, because many dermatologists mention that the aggravation of, for example, atopic dermatitis can be prevented only if the itching can be suppressed.
Such itching includes general pruritus which is defined as that is suppressible by commercially available antipruritic drugs such as anti-histamine drugs, and inveterate pruritus, which is defined as that cannot be suppressed by anti-histamine drugs nor by steroid drugs, such as dermal pruritus in hemodialysed patients, senile pruritus, and atopic dermatitis. The commercially available general antipruritic drugs based on anti-histamine agents are not only ineffective against inveterate pruritus, but also have the drawback of causing side effects such as drowsiness (central inhibition).
Although tacrolimus hydrate ointment, an immune suppressor, has recently been reported to be effective in treating atopic dermatitis (see JP2002-338537), this agent is not well-understood regarding its safeness and it is concerned that the agent may induce skin cancer and induce renal impairment when a significant amount is absorbed from an eroded site of the skin into the body.